Coolant pump

ABSTRACT

An axial-flow coolant pump mechanically driven by a pulley, a gear wheel, a plug-in shaft, or the like, for internal combustion engines uses a semi-axial impeller, a Francis impeller or diagonal impeller with three-dimensionally, spatially curved blades as the rotor, and the stator disposed in the pump housing possesses an inner guide cone that narrows in the flow direction, and an outer conical guide cap disposed to be spaced apart from the cone, and the two, spaced apart symmetrically, are connected by way of three-dimensionally, spatially curved stator vanes, wherein the rotor is spaced apart from the stator by a ring gap, in such a manner that the rotor has a minimal distance, not only, on the face side, from the adjacent outer edge of the guide cone, but also, on the face side, from the adjacent outer edge of the guide cap.

The invention relates to a coolant pump mechanically driven by a pulley, a gear wheel, a plug-in shaft, or the like, for internal combustion engines, in the design of an axial-flow coolant pump.

In the state of the art, axial-flow coolant pumps for internal combustion engines have been previously described. These are driven either by means of an electric motor, or also mechanically, by the crankshaft of the internal combustion engine, by way of pulleys or the like, for example.

The applicant presented an electrically driven, regulatable coolant pump for internal combustion engines, having an axial impeller, which has already proven itself in practice, in the design of a regulatable axial-flow-type coolant pump, in DE 100 47 387 A1.

Additional regulatable coolant pumps for internal combustion engines, having axial impellers, which have also already proven themselves in practice, were furthermore presented by the applicant in DE 102 07 653 C1 and in DE 103 14 526 B4.

Significant disadvantages of these aforementioned coolant pumps result, if from nothing else, from their drive, and since the electric motors are disposed within the coolant stream, the electric motors used, in each instance, can transfer only limited torques, due to the available construction space.

Furthermore, the necessarily required water-tight encapsulation of the electric motor necessarily results in higher production costs.

Furthermore, in the case of these solutions, as a result of the electrical components or electronic components used, upper limit values of temperature stress must always be adhered to, in order to prevent failure of these components.

Furthermore, after a “power failure,” “fail-safe” operation (continued functioning of the coolant pump after failure of the regulation system) cannot be guaranteed by means of these coolant pumps driven by an electric motor.

Furthermore, pumps with axial impellers (for example, including the design presented in DE 102 07 653 C1), have shown, in the case of suction-side throttling, that they require improvement in terms of flow mechanics, because cavitation phenomena and turbulence increasingly occur, which result in greater wear and also in power losses.

From DE 10 2006 034 952 B4, a mechanically driven pump having an axial impeller for the coolant circuit of an internal combustion engine is furthermore known. This coolant pump, structured as a regulatable axial pump, has a hollow shaft driven by a geared pulley, on which shaft multiple rotor blades are disposed, so as to rotate with it, in such a manner that their work angles can be adjusted mechanically, by way of a mechanism of effect disposed within the hollow shaft.

In this connection, activation of the mechanical adjustment mechanism takes place by way of an adjustment element that can be controlled electrically, electronically, hydraulically, or also pneumatically.

As a function of the work angle of the rotor blades, the coolant flowing through the pump housing is then accelerated to a greater or lesser degree.

By means of these aforementioned coolant pumps, in the design of a regulatable axial pump driven by a geared pulley, the cooling power and the drive power of the coolant pumps can be varied within specific limits, whereby the transferable torque, and therefore also the maximal conveyed volume stream, is limited by the “load-carrying capacity/durability” of the rotor blades, which are mounted in adjustable manner.

In DE 10 2008 048 893 A1, another mechanically driven pump for the coolant circuit of an internal combustion engine is previously described. In this design, an axial pump wheel mounted on one side is disposed in a pump housing, whereby the pump has two coolant exit openings, one of which can be closed completely by means of a regulation organ disposed behind the axial pump wheel.

The solution disclosed in DE 10 2008 048 893 A1, with mounting of the axial pump wheel on one side, has the disadvantages, however, that the smallest possible diameter of the pulley is limited by the bearing diameter, and that furthermore, mounting on one side has a negative influence on the required minimum gap dimensions on the axial pump wheel, so that due to the design-related, large gap dimension, losses in degree of efficiency necessarily have to be accepted.

Furthermore, an oil immersion pump for conveying crude oil from “non-flowing” oil sources is known from U.S. Pat. No. 4,865,519 A.

The rotor in this solution, previously described in U.S. Pat. No. 4,865,519 A, is coordinated with the special needs of conveying contaminated crude oil and is therefore provided with pressure relief bores, and furthermore has blade shapes specifically coordinated with the needs of use.

This solution, previously described in U.S. Pat. No. 4,865,519 A, is also characterized, among other things, in that the cover disk of the rotor, with a gap disposed on the mantle side, lies within the mantle of the stator, and that a large transition space is disposed between the rotor and the stator, which space is coordinated with the needs of crude oil conveying.

These characteristics of U.S. Pat. No. 4,865,519 A, which are essential to the invention, are required, in combination with the specially configured rotor blades and stator vanes, in order to implement oil conveying with reduced energy consumption, at clearly reduced production costs and a reduced pump size, by means of the oil immersion pump presented in U.S. Pat. No. 4,865,519 A, even with a single-stage head.

This solution according to U.S. Pat. No. 4,865,519 A, in connection with analogous use of this oil-conveying pump design as a motor vehicle coolant pump, would, however, necessarily lead to cavitation phenomena in the coolant medium, among other things, with all the disadvantages resulting from that, because of the temperature and rotational speed ranges in which coolant pumps operate.

In DE 10 2009 012 923 B3 the applicant furthermore presented another mechanically driven, regulatable coolant pump for internal combustion engines, which has also already proven itself in practice, in the design of a regulatable pump with an axial pump wheel mounted on two sides, in which the coolant exit opening can be completely closed by means of a regulation organ disposed behind the axial pump wheel.

This solution, with an axial impeller mounted on two sides, allows a clear reduction in the gap dimensions, and thereby clearly improves the degree of efficiency of the pump, among other things, as compared with the aforementioned designs.

All of the aforementioned designs have in common that the conveyed medium, the coolant, is introduced into the work region of the axial impeller approximately in arc shape, directly ahead of the axial impeller, in each instance, also by way of an inlet guide vane, and is conveyed from there into the pressure connector, which is provided either with or without a regulation device, by way of ring-cylindrical guide devices, stators. All the axial impellers used in the axial-flow coolant pumps of the state of the art are sensitive to cavitation and achieve a degree of efficiency of maximally 50% with their two-dimensional blade geometry, even at a minimal gap dimension, in the range of speeds of rotation that is usual for coolant pumps. In this connection, the limited construction space present in the engine compartment of a motor vehicle necessarily also allows only a greatly limited increase in pressure.

For the axial-flow coolant pumps previously described in the state of the art, an unstable progression of the characteristic curve of the coolant volume stream above the pump pressure at a constant rotational speed is furthermore characteristic, i.e. when a consumer is partly turned on or off in the coolant circuit at a constant rotational speed (engine rotational speed), then the coolant volume stream changes as a result.

Because of the unstable characteristic curve of these axial-flow coolant pumps of the state of the art, however, this results in a sudden, generally severe change in the pump pressure, in each instance, which has a very detrimental effect, in the case of the axial-flow coolant pumps of the state of the art.

The invention is therefore based on the task of developing an axial-flow pump for internal combustion engines that is mechanically driven by a pulley, a gear wheel, a plug-in shaft, or the like, which pump avoids the aforementioned disadvantages of the state of the art, and, with a reduced construction space/installation volume as compared with the state of the art, and the same pump shaft rotational speed, i.e. one that is usual for coolant pumps, allows a clear increase in pump pressure in axial-flow coolant pumps, and, at the same time, is characterized by a clearly improved, stable characteristic curve of the coolant volume stream above the pump pressure, at a constant rotational speed, as compared with the state of the art, furthermore is not sensitive to cavitation, prevents turbulence of the conveyed volume stream, at the same time guarantees a very high degree of efficiency, is furthermore characterized by a very compact, cost-advantageous, and robust design, which is simple in terms of production and installation technology, and guarantees great operational reliability and dependability, with a very long useful lifetime, even in the case of coolants charged with contaminants.

According to the invention, this task is accomplished by means of a coolant pump for internal combustion engines in the design of an axial-flow coolant pump, driven mechanically by a pulley, a gear wheel, a plug-in shaft, or the like, in accordance with the characteristics of the independent claim of the invention.

Advantageous embodiments, details, and characteristics of the invention are evident from the dependent claims and from the following description of the solution according to the invention, in connection with the representation of the solution according to the invention in the drawings.

In the following, the invention will now be explained in greater detail using an exemplary embodiment, in connection with a representation assigned to the exemplary embodiment, FIG. 1.

In this FIG. 1, a possible design of an axial-flow coolant pump for internal combustion engines, according to the invention, driven mechanically by a pulley 1, is shown in section, in a side view.

This axial-flow coolant pump according to the invention, having a pump housing 2, a flow entry opening 3 disposed on the housing on the suction side, and a flow exit opening 4 disposed on the pump housing on the pressure side, a pump shaft 6 rotatably mounted in/on the pump housing 2, by means of a pump bearing 5, connected with a pulley 1 so as to rotate with it, a pump shaft seal 8 disposed in the pump housing 2, between the latter and the pump shaft 6, on the drive side, next to the flow entry opening 3, in a seal seat 7, having a stator 9 disposed in the pump housing 2 in fixed manner, to prevent rotation, with guide vanes 10, in which stator a bearing accommodation 11 is situated, in which a slide bearing 12 is disposed, in which bearing the pump shaft 6 is mounted with its pump shaft end opposite the drive side, for example the pulley 1, whereby a rotor 14 with blades 15 is disposed on the pump shaft 6, so as to rotate with it, adjacent to the stator 9 with the slide bearing 12, in the direction of the flow entry opening 3, by a ring gap 13, is characterized, according to the invention, in that the rotor 14 is a semi-axial impeller, a Francis impeller or diagonal impeller with three-dimensionally, spatially curved blades 15.

Semi-axial impellers, Francis impellers, and diagonal impellers are characterized by a three-dimensionally, spatially curved blade geometry.

Under optimal general conditions, and at a minimal gap dimension, such semi-axial impellers, Francis impellers, and diagonal impellers can achieve a degree of efficiency of up to 80%, because of their spatially curved blades and the radial flow outlet, even at the speeds of rotation that are usual for coolant pumps.

As compared with the axial impellers used in axial-flow coolant pumps in the state of the art, semi-axial impellers, Francis impellers, and diagonal impellers are less sensitive to cavitation, and allow a clear increase in pressure, at limited construction space.

In this connection, it is essential to the invention that the pump shaft 6 mounted on both sides, in the pump bearing 5, on the one hand, and in a slide bearing 12 in the stator 9, on the other hand, guarantees a minimal ring gap 13 between the rotor 14 and the stator 9, whereby the rotor (14) is at a distance from the stator (9), by a minimal ring gap (13), in such a way that the rotor (14) has a minimal distance, not only, on the face side, from the adjacent outer edge of the guide cone (16), but also, on the face side, from the adjacent outer edge of the guide cap (17), by the ring gap (13), so that the stator entry edges that run parallel to the rotor exit edges form two seal gap geometries that are spaced apart from one another, thereby guaranteeing an optimal transition, in terms of flow geometry, of the conveyed volume stream that flows diagonally out of the rotor 14, directly into the stator 9 according to the invention.

The conveyed volume stream that exits from the rotor 14 diagonally toward the outside is optimally introduced into the stator 9 that has the structure according to the invention, adjacent at a minimal ring gap 13, because of the fact that the rotor 14 is not only spaced apart, on the face side, from the adjacent outer edge of the guide cone 16, but also, on the face side, from the adjacent outer edge of the guide cap 17, by a minimal ring gap 13 (a “seal gap”), in each instance, and immediately “deflected” in the stator 9, according to the invention, directly after the transition region delimited by the two seal gap geometries.

In this connection, the stator 9 according to the invention is characterized in that it possesses an inner guide cone 16 that narrows in the flow direction, and an outer conical guide cap 17 disposed to be spaced apart from the cone, and that the guide cone 16 is connected with the guide cap 17 by way of three-dimensionally, spatially curved stator vanes 10.

This space between the guide cone 16 and the guide cap 17, disposed in the stator according to the invention, equipped with spatially curved stator vanes 10, which space narrows toward the inside, according to the invention, now brings about the result that the conveyed volume stream, which first exits diagonally to the outside, out of the rotor 14 according to the invention, and immediately enters into the stator 9 again, being “deflected,” is converted into a conveyed volume stream that exits again from the stator 9 axially, during its entry, and during its flow through the stator 9 according to the invention, in the interior of the stator 9 according to the invention, on minimal construction space, almost free of loss, free of cavitation, and without turbulence, whereby cavitation phenomena can be excluded even in the range of high rotational speeds and even in the case of a hot coolant medium.

The coolant pump according to the invention, because of its robust structure, in terms of flow technology, furthermore guarantees great operational reliability and dependability, with a very long useful lifetime, even in the case of coolant charged with dirt.

This pump according to the invention, which is not sensitive to cavitation, guarantees a high degree of efficiency in its entirety, with minimal construction volume, and allows a clear increase in pressure despite a greatly limited construction space, and, in this connection, at the same time, is characterized by a very compact, cost-advantageous, and robust design, which is simple in terms of production and installation technology.

In this connection, it should be particularly emphasized that the coolant pump according to the invention is furthermore surprisingly characterized by a stable progression of the characteristic curve of the volume stream above the pump pressure, at a constant rotational speed, as compared with the axial-flow coolant pumps known in the state of the art, as a result of the arrangement and the interaction of the modules according to the invention.

In other words, if, for example, a consumer is partly turned on or off in the coolant circuit, at a constant rotational speed (engine rotational speed), the coolant volume stream necessarily changes immediately.

However, as compared with axial coolant pumps of the state of the art, having conventional axial impellers, this now no longer results in a change in the pump pressure, because of the stable characteristic curve according to the invention.

In this connection, the coolant pump according to the invention, as compared with axial coolant pumps of the state of the art, allows a very clear increase in pump pressure, at the same construction space/installation volume and the same rotational speed.

In test series, comparison values were determined using axial coolant pumps of the state of the art, equipped with axial impellers, at approximately the same construction space/installation volume, which values document that at a rotational speed of 12,000 rpm (high rotational speed range), a pump pressure of approximately 1 bar can be achieved with conventional axial coolant pumps.

In contrast, a significantly higher pump pressure of about 1.7 bar was achieved by means of the axial coolant pump according to the invention, as presented here, with the same construction space and an analogous rotational speed of 12,000 rpm.

It is also characteristic that an inflow chamber 19 having an inside diameter D, which has rotation symmetry relative to the pump shaft 6, is situated in the pump housing 2, directly ahead of the rotor 14, the chamber length L of which chamber amounts to approximately 0.7 to 1.5 times the inside diameter D.

The design shown in FIG. 1 has an inflow chamber 19, the chamber length L of which amounts to approximately 0.9 times the inside diameter D.

This inflow chamber 19 according to the invention brings about undisturbed inflow, particularly serves for “uniformization” of the intake volume stream, and thereby clearly contributes to further optimization of the effects according to the invention.

It is also essential to the invention that a guide tongue 18 is disposed at the free end of the guide cap 17, on the flow exit side.

This guide tongue 18 prevents turbulence formation in the region of the pressure-side flow exit, according to the invention, and likewise serves for further optimization of the effects according to the invention.

However, the solution according to the invention, in its entirety, also brings about the result that the solution according to the invention, in comparison with the axial-flow coolant pumps of the state of the art, requires a clearly lower drive power of the pump shaft 6, when the main flow channel 21 is completely closed/throttled, so that the degree of efficiency of the axial-flow coolant pump according to the invention is increased even further in this way.

In this design, shown in FIG. 1, a coolant exit flange 20 with the main flow channel 21 is disposed on the pump housing 2 of the axial-flow coolant pump according to the invention, in the region of the flow exit opening 4.

This main flow channel 21 empties into the coolant circuit, as is usual in the state of the art, and makes optimal cooling of the cylinder crankcase, the cylinder head, the exhaust manifold, as well as cooling of special components, such as, for example, of the exhaust reflux, of the exhaust manifold, but also heat supply to the heating system of the passenger compartment, and more of the like, possible, for example in connection with actuators.

REFERENCE SYMBOL LIST

1 pulley

2 pump housing

3 flow entry opening

4 flow exit opening

5 pump bearing

6 pump shaft

7 seal seat

8 pump shaft seal

9 stator

10 guide vane

11 bearing accommodation

12 slide bearing

13 ring gap

14 rotor

15 blade

16 guide cone

17 guide cap

18 guide tongue

19 inflow chamber

20 coolant exit flange

21 main stream channel

D inside diameter

L chamber length 

1-4. (canceled)
 5. Coolant pump in the design of a coolant pump mechanically driven by a pulley (1), a gear wheel, a plug-in shaft, or the like, for internal combustion engines, having a pump housing (2) with a flow entry opening (3) and a flow exit opening (4), a pump shaft (6) rotatably mounted in/on the pump housing (2) by means of a pump bearing (5), connected with a pulley (1) so as to rotate with it, a pump shaft seal (8) disposed in the pump housing (2), between the latter and the pump shaft (6), on the drive side, next to the flow entry opening (3), in a seal seat (7), having a stator (9) disposed in the pump housing (2) in fixed manner, to prevent rotation, with guide vanes (10), in which stator a bearing accommodation (11) is situated, in which a slide bearing (12) is disposed, in which bearing the pump shaft (6) is mounted with its pump shaft end opposite the drive side, for example the pulley (1), wherein a rotor (14) with blades (15) is disposed on the pump shaft (6), so as to rotate with it, adjacent to the stator (9) with the slide bearing (12), in the direction of the flow entry opening (3), by a ring gap (13), and wherein the flow entry opening (3) is disposed to the side of the center axis of the pump shaft (6), so that the flow entry takes place at a slant to the axis of rotation of the rotor (14), wherein the rotor (14) is a semi-axial impeller, a Francis impeller or diagonal impeller with three-dimensionally, spatially curved blades (15), and wherein the stator (9) disposed in fixed manner in the pump housing (2) possesses an inner guide cone (16) that narrows in the flow direction, and an outer conical guide cap (17) disposed to be spaced apart from the cone, and wherein the guide cone (16) is connected with the guide cap (17), spaced apart symmetrically, by way of three-dimensionally, spatially curved stator vanes (10), and wherein the rotor (14) is spaced apart from the stator (9) by a minimal ring gap (13), wherein the rotor (14) has a minimal distance, not only, on the face side, from the adjacent outer edge of the guide cone (16), but also, on the face side, from the adjacent outer edge of the guide cap (17), by the ring gap (13), wherein an inflow chamber (19) having an inside diameter (D), disposed with rotation symmetry relative to the pump shaft (6), is situated in the pump housing (2), directly ahead of the rotor (14), the chamber length (L) of which chamber amounts to approximately 0.7 to 1.5 times the inside diameter (D).
 6. Coolant pump according to claim 5, wherein a guide tongue (18) is disposed at the free end of the guide cap (17).
 7. Coolant pump according to claim 5, wherein a coolant exit flange (20) is disposed on the pump housing (2) in the region of the flow exit opening (4). 